Dietary saturated fatty acids intake is known to be a major risk factor in heart disease in humans, particularly in countries where the population is well-nourished. Animal products, such as dairy products (especially milk), are major contributors to the dietary intake of humans. It is generally accepted that the level of saturated fatty acids found in milk, particularly those with a chain length of less that 18 carbon atoms, is a risk factor in coronary heart disease. In contrast, unsaturated fatty acids are considered to be beneficial. Because of this, there has been a preference for the consumption of plant derived oils as opposed to animal based products.
The medical community is also concerned about the consumption of fat found in milk because of the abundance of the saturated fatty acid C:14:0, which is thought to be atherogenic. The dairy industry has in part responded with the production of “low fat” milk alternatives using chemical separation and extraction techniques.
In addition to fats, specific protein components of milk, including the A1 variant of the β-casein protein, are health risk factors. There are a number of reports that the consumption of β-casein A1 by humans is linked with a higher incidence of certain diseases, specifically diabetes (Elliott et al. 1999 Diabetologia 42:292-6; Wasmuth et al. 1999 Diabetologia 42 (Suppl. 1):A88 Proceedings of the Kongress der Europäischen Diabetesgesellschaft vom 28.-30.09.1999 in Brüssels/Belgium) and coronary heart disease (McLachlan, C. N., Med. Hypotheses 56(2):262-72, 2001).
In addition to phenotyping a cow by identifying the particular β-casein variant or variants produced in the cow's milk, it is well known that a cow can be genotyped for a specific single nucleotide polymorphism (SNP) to determine which β-casein variant or variants she will produce in her milk. A method of selecting bovine cows on the basis of this genotyping methodology to give milking herds which will produce milk free of the β-casein A1 variant, and preferably solely the β-casein A2 variant, is the subject of PCT/NZ96/00039 (published as WO 96/36239).
The applicant has now found that there is a correlation between the ratio of saturated to unsaturated fatty acids in milk and the β-casein variants in milk. While there are known methods of altering the fatty acid composition of animal products, these typically include chemical extraction, specific feeding and management systems, and quantitative genetic selection for levels of specific fatty acids in milk. Each method is costly and usually inefficient.
It is therefore an object of the invention to provide milk, or a product obtained from that milk, which has a reduced level of saturated fatty acids relative to unsaturated fatty acids, or to at least provide the public with a useful alternative.